Systems for setting the pressure of the cylinders of a printing station or a printing press are known in the art. The pressure of the cylinders is set for achieving sufficient print quality, on the one hand, and for reducing ink waste, on the other hand. That is, excessive pressure might increase ink waste and might even deteriorate print quality, for example, by smearing ink. On the other hand, insufficient pressure might lead to lack of ink coverage and an incomplete printed image. Each cylinder is actuated by two actuators (i.e., also referred to as motors or engines) coupled at either end of the cylinder. That is, setting the pressure involves setting the pressure of each of the actuators.
Methods for setting up the pressure of the printing press cylinders are known in the art. In a manual method, the operator runs the printing press, inspects the printed image, and adjusts the pressure between the rollers, until the printed image is acceptable. Automatic set up methods are also known in the art, as detailed herein below.
U.S. Pat. No. 6,634,297 B2 issued to Poetter et al., and entitled “Device and Process for Setting the Printed Image in a Flexographic Press”, is directed to a system for setting up a printing job. The desired contour of the image which is to be printed on the paper web is entered into a control and regulating unit. The diameter of the printing roller and the thickness of the blocks are further entered into the control and regulating unit. A camera scans the printed image and feeds the scanned image to the control and regulating unit. The control and regulating unit compares the scanned image with the desired contour, and directs an actuating device to control the servo motors of the cylinders to move the cylinders to a position, which produces the qualitatively best printed image. The values respective of this position are stored in a storage of the control and regulating unit, so that the optimal setting can be found again.
U.S. Pat. No. 5,448,949 issued to Bucher and entitled “Method and Device for Adjusting a Contact Pressure between Ink-Carrying Cylinders of a Printing Machine”, is directed to a system for setting up a printing job. During printing, a contact strip is formed on the surface of the printing form. Two opto-electronic sensors sense the contact strip. A control or regulating device determines the width of the contact strip, according to outputs of an angular position sensor and two opto-electronic sensors. The control or regulating device directs an adjusting drives to move the rollers, according to the width of the contact strip, in order to adjust the contact pressure of the rollers.
U.S. Pat. No. 5,841,955 issued to Wang and entitled “Control System For a Printing Press”, is directed to a system for adjusting various parameters of a printing press, in real-time, by comparing the variation of ink distribution for each of the cyan, magenta, yellow and black colors, in a current copy, with those in a reference copy.